CN110926367A - Long-range optical surface shape detection device and detection method - Google Patents
Long-range optical surface shape detection device and detection method Download PDFInfo
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- CN110926367A CN110926367A CN201911303272.8A CN201911303272A CN110926367A CN 110926367 A CN110926367 A CN 110926367A CN 201911303272 A CN201911303272 A CN 201911303272A CN 110926367 A CN110926367 A CN 110926367A
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Abstract
The invention relates to a long-range optical surface shape detection device and a detection method, wherein the surface shape detection device comprises a detection light path and an f-theta angle detection system for forming a measurement light spot, a double-wedge mechanism is arranged on an incident light path directly incident to the surface of an optical device to be measured in the detection light path, the double-wedge mechanism comprises two single wedge wedges arranged at intervals along the incident light path, the incident light path penetrates through the two single wedge wedges, and the two single wedge wedges can independently rotate to change the angle of an emergent light path of the single wedge through rotation and enable the emergent light path to be incident to the surface of the optical device to be measured in a normal incidence mode. The invention makes the reflected light path return along the incident light path original path by rotating the wedge and can be judged by combining the measuring light spot, the surface shape of the optical device to be measured is obtained by the rotating amount of the wedge, the action positions of the light path on each optical element are consistent, the angle error of each optical element caused by the transverse moving amount in the traditional system can be completely avoided, and the detection precision is improved.
Description
Technical Field
The invention belongs to the technical field of surface shape detection of long-range mirrors, and particularly relates to a long-range optical surface shape detection device and a detection method.
Background
With the continuous development of science and technology, various application fields put higher requirements on the detection of the surface shape of the mirror surface. In order to improve the detection capability of the long-range profilometer, various system errors of the long-range profilometer need to be corrected or eliminated. Of these systematic errors, the most important one is introduced due to the slight difference between the optical elements used in the optical path system of the long-range profilometer itself and the ideal optical elements, which mainly appears in two aspects:
on one hand, the system error is introduced by the tiny processing difference between the surface shape of each reflection optical element in the optical path system and the surface shape of an ideal reflection optical element and the uneven material refractive index of the transmission optical element, and when a measuring beam is incident on a non-ideal optical element, the non-ideal optical element causes the direction of an emergent beam to slightly deviate from the ideal emergent direction, so that the angle measuring error is introduced;
on the other hand, the light beam reflected by the optical device to be measured can generate transverse movement on each optical element in the system along with the change of the measurement angle, the farther the light beam is away from the surface to be measured, the larger the transverse movement amount is, the more errors are introduced to different points on the same optical element in the measurement system, and more system errors can be introduced. The amount of lateral shift, processing defects and aberrations all introduce angular measurement errors.
For example, in CN105737758A, the pp-LTP optical structure shown in fig. 1 has a phase plate 2', a beam splitter 3', a plane mirror 4', a pentaprism 5', and a fourier transform lens 7' of an f- θ angle detection system introduced into its detection optical path, which all introduce the above system errors, so that CN105737758A adopts a new structure of a single-aperture screen, so that the optical elements introducing errors only include the plane mirror and the fourier transform lens, thereby reducing the number of optical elements introducing system errors, reducing the amount of lateral shift, and improving the detection accuracy.
There is also a detection optical path structure disclosed in CN105737759A, in which the f- θ angle detection system is disposed on the mobile optical head, so that the structure is more compact, the amount of lateral shift is reduced, and the optical element introducing errors is only a fourier transform lens.
There is also a detection optical path structure disclosed in CN105758333A, and an f- θ angle detection system is also disposed on the moving optical head, and the optical element introducing the error is only a beam splitter.
There is also a detection optical path structure disclosed in CN105674913A, and the optical elements for introducing errors only include a beam splitter and a fourier transform lens.
As can be seen from the above, in the existing long-range profile measurement solutions, the purpose of reducing the optical elements and the optical elements introducing errors is achieved by structural changes, and the systematic errors cannot be completely or better eliminated, and the form of the surface shape of the measured optical device is fed back through the difference value between the falling points of the measuring light spots on the area array detector (CCD) of the f-theta angle detection system, and the problems of processing nonuniformity of the pixel points of the area array detector, inconsistent photoelectric response efficiency, consistency of electronic circuits and the like brought into system errors also inevitably exist, theoretically, the larger the distance between the Fourier transform lens and the area array detector is, the higher the resolving power is, in the current detection mode, the larger the distance is, the more errors are introduced into different points on an area array detector (CCD), and the contradiction exists.
The wedge-shaped wedge used by wedge interference is often cited in the current optical products or experiments, and the variable optical path paths such as CN108317959A, CN109579708A and CN208042993U are related by rotation, so that the applicant considers that the wedge-shaped wedge is skillfully applied to the surface shape detection of the long-range surface shape mirror surface, and the precision of the long-range surface shape measuring equipment can be further improved.
Disclosure of Invention
In view of the above-mentioned deficiencies of the prior art, the present invention provides a long-range optical surface profile detection apparatus and a detection method, which avoid the problem of system errors caused by profile errors, refractive index errors and lateral displacement of optical elements in a detection optical path, and achieve the effects of reducing introduction of system errors and improving detection accuracy.
In order to solve the technical problems, the invention adopts the following technical scheme:
the long-range optical surface shape detection device comprises a detection light path and an f-theta angle detection system for forming a measurement light spot, wherein a double-wedge mechanism is arranged on an incident light path which is directly incident to the surface of an optical device to be measured in the detection light path, the double-wedge mechanism comprises two single wedge wedges which are arranged at intervals along the incident light path, the incident light path penetrates through the two single wedge wedges, and the two single wedge wedges can independently rotate to change the angle of an emergent light path of the single wedge mechanism through rotation and enable the emergent light path to be incident to the surface of the optical device to be measured in a normal incidence mode; the surface shape of the optical device to be measured is obtained through the rotation quantity of the two single wedge wedges.
The technical scheme is further perfected, the detection light path comprises a light source, a beam splitter and two plane reflectors forming an equivalent pentaprism, the f-theta angle detection system comprises a Fourier transform lens and a plane array detector, the light source, the beam splitter, the Fourier transform lens and the plane array detector are fixedly arranged, the two plane reflectors and the double-wedge mechanism are arranged on the movable optical head, an emergent light beam provided by the light source is reflected to the two plane reflectors through the beam splitter, reflected by the two plane reflectors, penetrates through the double-wedge mechanism to be incident on the surface of the optical device to be detected, then is reflected by the surface of the optical device to be detected and returns to the beam splitter along an incident light path, and the reflected light beam penetrates through the beam splitter and is transmitted to the plane array detector through the Fourier transform lens, so that the measurement light spot is formed on the plane array detector.
Furthermore, the movable optical head comprises a shell, and the two plane reflectors and the double wedge mechanism are arranged in the shell.
Further, the movable optical head is installed on a linear translation table, the linear translation table is slidably arranged above the optical platform so as to drive the movable optical head to slide and detect the optical device to be detected, the optical device to be detected is arranged on the optical platform, and the light source, the beam splitter, the Fourier transform lens and the area array detector are fixedly arranged on the side wall of the optical platform.
Further, the light source is a parallel light source to provide an outgoing beam of parallel light.
Further, the light source is an incoherent light source.
Furthermore, the two single wedge wedges are adjacent, the opposite surfaces of the two single wedge wedges are horizontal glass surfaces which are parallel to each other, and the opposite surfaces of the two single wedge wedges are inclined glass surfaces which form a wedge shape, so that the distance between the two single wedge wedges which are arranged adjacently can be smaller.
The invention also relates to a long-range optical surface shape detection method which is carried out based on the long-range optical surface shape detection device and comprises the following steps:
1) placing an optical device to be tested on an optical platform;
2) the linear translation stage drives the movable optical head to slide to a first detection point, an emergent light beam provided by the light source is reflected by the surface of the optical device to be detected, and a measurement light spot is formed on the area array detector;
3) rotating the two single wedge wedges to enable the emergent light path to be incident to the surface of the optical device to be measured in a normal incidence mode, and judging whether the measuring light spots are formed in a unified set range on the area array detector;
if the measuring light spot is formed in the unified setting range, outputting the rotation data of the two single wedge wedges;
if the measuring light spot is not formed in the unified setting range, continuing to rotate and adjust until the measuring light spot is formed in the unified setting range, and then outputting the rotation data of the two single wedge wedges;
4) the linear translation stage drives the movable optical head to slide to the next detection point, an emergent light beam provided by the light source is reflected by the surface of the optical device to be detected, and a measurement light spot is formed on the area array detector;
5) repeating the steps 3) and 4) until the set rotation data of the two single wedge wedges corresponding to all the detection points are output;
6) and obtaining the surface shape of the optical device to be measured through the obtained rotation data.
Further, before the step 1), a calibration operation of the device is further included, and the calibration operation includes determining the uniform setting range through a measurement light spot formed on the area array detector by a reflection light path returned by the incident light path.
Further, the calibration operation includes the following steps:
a) a single-hole screen is closely arranged on the beam splitter;
b) placing a calibration piece on the optical platform;
c) an emergent light beam provided by the light source penetrates through a screen hole of the single-hole screen, is reflected to the two plane reflectors through the beam splitter, penetrates through the double-wedge mechanism after being reflected by the two plane reflectors, is incident on the surface of the calibration piece, and is reflected by the surface of the calibration piece to form a reflection light path;
and adjusting the posture of the calibration part to enable the reflected light path to return along the original path of the incident light path, penetrate through the screen hole of the single-hole screen, penetrate through the beam splitter and transmit to the area array detector through the Fourier transform lens, and form a measuring light spot on the area array detector.
Compared with the prior art, the invention has the following beneficial effects:
1. the surface shape detection device of the invention can change the angle of the emergent light path penetrating out of the double wedge mechanism and make the emergent light path incident on the surface of the optical device to be detected in a normal incidence mode by adding the double wedge mechanism in the detection light path and rotating the two single wedge wedges of the double wedge mechanism, because the incident light path is vertical incidence, the reflection light path of the detection point returns along the original path of the incident light path, and the incident light path part before the incident light path enters the double wedge mechanism is consistent all the time, therefore, the falling points of the measurement light spots formed by the reflection light paths of different detection points can be consistent or all fall within the set falling point range (the absolute falling point consistency can not be realized, so the concept of the falling point range is also used), and the surface shape of the optical device to be detected is obtained by the rotation quantity and the measurement position of the two single wedge wedges. Thus, the surface shape detection condition is not fed back directly through the distance difference between the measuring light spots on the area array detector, but only as an intermediate reference and just as an effect observation point or a feedback point for the rotation adjustment of two single wedge wedges, so that the detection light path is always kept on the same route, the action positions of the light beams on each optical element on the detection light path are all fixed and are in the same point or a small range, and the surface shape detection condition comprises an area array detector! The problem that system errors are possibly introduced into optical elements in a detection light path is fundamentally overcome, the introduction of the system errors is effectively reduced, the angle errors of the optical elements (a reflecting mirror surface, a transmission body, a Fourier lens and a CCD) introduced by the beam transverse displacement in the traditional system can be completely avoided, and the detection precision is improved.
2. In the detection form of the invention, because the measured light spots have consistent falling points, the distance between the Fourier transform lens and the area array detector can be larger without introducing excessive errors at different points, thereby overcoming the contradiction in the existing form, improving the resolution capability of the used f-theta angle detection system and correspondingly improving the judgment precision of the consistency of the measured light spots when in detection use.
3. The angle is measured by a double-wedge method, the system angle measurement range is controlled by the size of a wedge angle (if the vertex angles of the double wedges are 5mrad, the system measurement range is +/-5 mrad), the surface shape angle measurement range (such as +/-5 mrad) is expanded and corresponds to the wedge angle adjustment range of 0-pi by the double wedges, if the rotation angle of the wedges can realize the angle precision of 10mrad, the system can theoretically realize the angle measurement precision superior to 50 mrad in the angle measurement range of +/-5 mrad, and the measurement method is not limited by the measurement distance. The measurement accuracy of the currently known maximum-accuracy long-range surface-shaped system can only achieve 50nrad within the range of about +/-250 mu rad.
Drawings
FIG. 1 is a schematic diagram of a long-range optical surface profile inspection device according to an embodiment;
FIG. 2 is an enlarged partial schematic view of FIG. 1;
FIG. 3 is a schematic diagram of controlling the measurement range by rotation of the double wedge mechanism in an exemplary embodiment;
FIG. 4 is a diagram illustrating the effect of normal incidence and road reflection at a detection point in an embodiment (solid line);
FIG. 5 is a diagram illustrating a simulation of the relationship between angles associated with the exit light path during use in accordance with an exemplary embodiment;
FIG. 6 is a graph of the θ angle transformation in use of an embodiment;
FIG. 7 is a α angle transformation diagram of an embodiment in use;
FIG. 8 is a graph of the theta angle difference transformation in use according to an embodiment;
FIG. 9 is a schematic diagram of a calibration structure of an embodiment;
the device comprises a light source 1, a beam splitter 2, a plane mirror 3, a double-wedge mechanism 4, a single wedge 41, an optical device 5 to be measured, a Fourier transform lens 7, an area array detector 8, an optical platform 10, a linear translation stage 11, a shell 12, a single-hole screen 100 and a calibration piece 101.
Detailed Description
The following describes embodiments of the present invention in further detail with reference to the accompanying drawings.
Referring to fig. 1 and 2, the long-range optical surface profile detection apparatus of the embodiment is used for performing surface profile detection on a surface of an optical device 5 to be detected, and includes a detection light path and an f- θ angle detection system for forming a measurement light spot, in the detection light path, an incident light path directly incident on the surface of the optical device to be detected is provided with a double wedge mechanism 4, the double wedge mechanism 4 includes two single wedge wedges 41 arranged at intervals along the incident light path, the incident light path passes through the two single wedge wedges 41, the two single wedge wedges 41 can rotate independently to change an angle of an emergent light path thereof by rotation and make the emergent light path incident on the surface of the optical device to be detected in a normal incidence manner, and further, the surface profile of the optical device to be detected can be fed back by rotation amount of the two single wedge 41. It will be appreciated that the rotation of the two single wedge wedges 41 is along the optical axis.
The surface shape detection device of the embodiment adds the double wedge mechanism 4 into the existing detection light path, and by rotating the two single wedge wedges 41 of the double wedge mechanism 4, the angle of the emergent light path penetrating through the double wedge mechanism 4 can be changed and the emergent light path is made to enter the surface of the optical device to be detected in a normal incidence mode, because the incident light path is vertical incidence, the reflection light path of the detection point returns according to the original path of the incident light path, and the incident light path part before entering the double wedge mechanism 4 is always consistent, therefore, the falling points of the measurement light spots formed by the reflection light paths of different detection points can be consistent or all fall within the set falling point range, at this time, the falling point position of the measurement light spot is no longer a direct judgment value, only the rotation adjustment reference and observation feedback point of the single wedge 41, but the rotation angles of the two single wedge wedges 41 feed back the surface shape deflection angles corresponding to the different detection point positions, therefore, the surface shape of the optical device to be detected can be obtained.
The surface shape of the optical device to be measured is fed back through the rotation quantity of the two single wedge wedges 41. In such a form, the surface shape detection condition is not fed back directly through the distance difference between the measurement light spots on the f-theta angle detection system, but only as an intermediate reference, namely as an effect observation point or a feedback point for the rotation adjustment of the two single wedge wedges 41; the detection light path is always kept on the same route, the position of the light beam on each optical element on the detection light path is fixed and is in the same point or a small range, the area array detector 7 in the f-theta angle detection system is included, when different angles are measured, the transverse displacement of the measuring light beam on each optical element is zero, the angle errors introduced between the optical elements when the different angles are measured are the same, no error exists in the relative difference value between the measuring angles, and the relative difference value between the angles is a required measurement value which can feed back the surface shape of the optical device to be measured. Therefore, the problem that system errors are possibly introduced into each optical element in a detection light path is fundamentally solved, the introduction of the system errors is effectively reduced, and the detection precision is improved. The surface shape of the optical device to be detected is fed back through the rotation quantity of the two single wedge wedges 41, and the adjustable range is changed to be adjusted on the measuring range of 0-pi arc value, so that the reading precision is enlarged, the reading interval is subdivided, and the effect of further improving the detection precision is achieved.
The rotation precision that present mechanical structure can reach 10 mu rad angle precision (for example current AEROTECH precision rotary table, can realize positioning accuracy 2arc sec, about 10urad, if hope to realize higher measurement accuracy, can select higher positioning accuracy rotary table), can support the rotation regulation of monomer wedge 41 that needs and the adjustment of light path angle completely, and the double wedge mechanism 4 that adds, according to its light path characteristic, it can not influence its rotation angle of emergent light path even receive vibration (in current machining control precision), so can ensure above-mentioned effect, and do not introduce other problems that influence and detect the precision. Finally, the problem of introducing the transverse displacement amount exists in the two single wedge wedges 41, but because the distance between the two single wedge wedges 41 can be adjacently arranged, the introduced transverse displacement amount is very small, and the influence on the detection accuracy is negligible, for example, the transverse displacement amount introduced by the double-wedge mechanism 4 is very small because the vertex angle of the single wedge 41 is calculated as 5mrad, the emergent light deflection angle is 2.5mrad, the distance between the two single wedge wedges 41 is calculated as 1cm, the introduced transverse displacement amount is 25 μm, and the diameter of the light spot is usually 1mm (even larger), and the distance between the two single wedge wedges 41 can be smaller. In order to reduce the distance between the two single wedge wedges 41, it is preferable that the two single wedge wedges 41 are adjacent to each other, and the opposite surfaces of the two single wedge wedges 41 are horizontal glass surfaces parallel to each other and inclined glass surfaces forming a wedge shape, so that the distance between the two single wedge wedges 41 which are adjacently arranged can be reduced, as shown in fig. 4. It will be appreciated that other arrangements of lamination may be used.
Wherein, the detection light path comprises a light source 1, a beam splitter 2 and two plane reflectors 3 forming an equivalent pentaprism, the f-theta angle detection system comprises a Fourier transform lens 6 and a plane array detector 7, the light source 1, the beam splitter 2, the Fourier transform lens 6 and the plane array detector 7 are fixedly arranged, the two plane reflectors 3 and the double-wedge mechanism 4 are arranged on the mobile optical head, an emergent light beam provided by the light source 1 is reflected to the two plane reflectors 3 through the beam splitter 2, then is reflected by the two plane reflectors 3 and is emergent perpendicular to an incident light beam reflected by the beam splitter 2, passes through the double-wedge mechanism 4 and is incident on the surface of the optical device to be measured 5, the two single wedge points 41 are rotationally adjusted, so that an incident light path passing through the double-wedge mechanism 4 is incident on the surface of the optical device to be measured 5 along the normal direction, then is reflected by the surface of the optical device to be measured 5 and returns to the beam splitter 2 along the original incident light path, the reflected light beams penetrate through the beam splitter 2, are converged through the Fourier transform lens 6 and then are transmitted to the area array detector 7, and the measuring light spots are formed on the area array detector 7.
Therefore, a specific detection light path form is provided, the method is simple and reliable, the problem of uneven refractive index can be avoided by adopting the two plane reflecting mirrors 3 to replace a pentaprism, and the pentaprism can be selected and used in implementation.
The movable optical head comprises a shell 12, and the two plane reflectors 3 and the double-wedge mechanism 4 are arranged in the shell 12. The movable optical head is installed on a linear translation table 11, the linear translation table 11 is slidably arranged above an optical platform 10 so as to drive the movable optical head to slide and detect an optical device 5 to be detected arranged on the optical platform 10, and the light source 1, the beam splitter 2, the Fourier transform lens 6 and the area array detector 7 are fixedly arranged on the side wall of the optical platform 10.
Thus, the necessary infrastructure is provided, and the moving optics head, linear translation stage 11 and the optical stage 10 are all prior art and will not be described further herein.
Wherein the light source 1 is a collimated light source such that the provided outgoing light beam is a collimated light beam, and preferably a collimated incoherent beamlet. In practice, coherent light, such as a laser light source, may be optionally used to provide the outgoing beam as a parallel coherent beamlet.
The angle is measured by the double-wedge mechanism 4, the angle measuring range of the device is controlled by the size of the top angle of the wedge, a light beam always deflects towards the thicker side of the light beam passing through the wedge, if the top angle of the wedge is 5mrad, the measuring range is +/-5 mrad, as shown in fig. 3, the thicker ends of the two single wedge wedges 41 are consistent in orientation, the emergent light path passing through the double-wedge mechanism 4 reaches the maximum deflection angle of 5mrad, when the device is used, the angle of the emergent light path passing through the double-wedge mechanism 4 can be (randomly) changed within the conical geometric body range of the half cone angle of 5mrad by rotating the two single wedge 41, an incident point which is incident by a normal can be found within the measuring range, as shown in fig. 4, if the incident point cannot be found, the placing posture of the optical device 5 to be measured on the optical platform 10 is not over the measuring range; the incident point and the set detection point are not overlapped usually, the relative position of the incident point and the set detection point can also be calculated through the rotation angle of the single wedge-shaped wedge 41, and the surface shape to be measured can be constructed through the integration between the angle and the position.
The thicker ends of the two single wedge wedges 41 face the same direction, the emergent light path passing through the double wedge mechanism 4 reaches the maximum deflection angle of 5mrad, the thicker ends of the two single wedge wedges 41 face the same direction and rotate in the same direction, the emergent light path rotates in the circumferential direction at the maximum deflection angle (i.e. rotates along the axis of the conical geometry in the form of a bus), and the emergent light path can stay at any position in the circumferential direction. When the single wedge-shaped wedge-. The surface shape angle measuring range (+ -5 mrad) is expanded and corresponds to the range of 0-pi of the angle adjustment of the wedge through the double wedge mechanism 4 (if the angle is continuously rotated to 2 pi from pi, the emergent light path returns to the state of +5mrad along-5 mrad in figure 3, and the adjustment is repeated), if the angle of the wedge at intervals is rotated to realize the angle accuracy of 10mrad, the device can realize the angle measuring accuracy better than 50 mrad in the angle measuring range of +/-5 mrad, and the measuring mode is not limited by the measuring distance. The measurement accuracy of the currently known maximum-accuracy long-range surface-shaped system can only achieve 50nrad within the range of about +/-250 μ rad, and theoretically, the device can detect and ensure the measurement accuracy within 20 times of the measurement range and achieve at least the optimal measurement accuracy.
When the double-wedge mechanism 4 is rotated, the variation of the emergent light path angle along with the rotation of the double-wedge mechanism 4 in the measuring direction is within the range of +/-5 mrad and the variation of the emergent light path angle along with the rotation of the double-wedge mechanism 4 in the vertical direction is not large, as shown in fig. 8, the difference of the adjacent theta variation values when the double-wedge mechanism 4 is reversely changed by 10mrad can be obtained, the variation of the adjacent theta variation values can be seen, the variation of the theta variation angles can be seen, the variation of the single theta variation angles can be seen, the variation of the theta variation angles can be seen, the range of the theta variation angles can be seen is not larger than the range of 0mrad, and the theta variation angle can be seen, the variation of the theta variation can be seen, the single theta variation angle can be seen, the variation can be seen, and the variation of the theta variation can be seen, the range of the theta variation can be seen, the phi variation.
Referring to fig. 1, the present invention further provides a long-range optical surface shape detection method, which is performed based on the long-range optical surface shape detection apparatus, and includes the following steps:
1) placing the optical device 5 to be tested on an optical platform 10;
2) the linear translation stage 11 drives the shell 12 of the mobile optical head to slide to a first detection point, the light source 1 provides an emergent light beam, the emergent light beam is reflected by the surface of the optical device 5 to be detected, and a measurement light spot, namely a dotted light path in the figure, is formed on the area array detector 7;
3) rotating the two single wedge wedges 41 to enable the emergent light paths to enter the surface of the optical device to be measured 5 in a normal incidence mode, judging whether the measuring light spots are formed in a unified set range on the area array detector 7 (namely whether the measuring light spots fall in a set falling point range), and adjusting the dotted light paths in the graph to be coincident with the solid light paths;
if the measuring light spot is formed in the unified setting range, outputting (recording) the rotation data (rotation angle) of the two single wedge wedges 41;
if the measuring light spot is not formed in the unified setting range, continuing to rotate and adjust according to the measuring data until the measuring light spot is formed in the unified setting range, and then outputting the rotating data of the two single wedge wedges 41; during implementation, if the measuring light spot is not formed in the unified setting range, the normal angle direction can be judged according to the forming position of the measuring light spot, so that the rotating angle of the double wedge mechanism 4 is corrected, and the rotation adjustment of the two single wedge wedges 41 is facilitated;
4) the linear translation stage 11 drives the movable optical head to slide to the next detection point, the light source 1 provides an emergent light beam, and the emergent light beam is reflected by the surface of the optical device to be detected to form a measurement light spot on the area array detector;
5) repeating the steps 3) and 4) until the set rotation data of the two single wedge wedges 41 corresponding to all the detection points are output;
the measurement light spots formed on the area array detector 7 by different detection points all fall within the same set fall point range (the unified set range), that is, the fall points are consistent, and the absolute fall point consistency cannot be realized, so that the fall points are limited within a smaller set range by combining the detection mode of the area array detector 7.
6) The surface shape of the optical device 5 to be measured can be obtained through the obtained rotation data and the measurement position.
Referring to fig. 9, before step 1), a calibration operation of the apparatus is further included, and the calibration operation includes determining the uniform setting range by a measurement spot formed on the area array detector by a reflected light path returned by the incident light path. The method specifically comprises the following steps:
a) a single-hole screen 100 is closely arranged at the incident position of parallel light on the surface of the beam splitter 2 facing the light source 1;
b) placing a calibration piece 101 on the optical platform;
c) parallel light emergent beams provided by the light source 1 penetrate through a screen hole of the single-hole screen 100 and are reflected to the two plane reflectors 3 through the beam splitter 2, the parallel light emergent beams are reflected by the two plane reflectors 3 and then penetrate through the double-wedge mechanism 4 to be incident on the surface of the calibration piece 101, and a reflection light path is formed through the surface reflection of the calibration piece 101; according to the reversible optical path, at this time, if the reflected optical path fails to return by the original path of the incident optical path, the reflected optical path is incident on the non-screen hole position on the single-hole screen 100 and is blocked, and only the reflected optical path returned by the original path of the incident optical path can pass through the screen hole of the single-hole screen 100. Therefore, the attitude of the standard component 101 only needs to be adjusted, so that the reflected light path returns along the original path of the incident light path (normal incident attitude), passes through the screen hole of the single-hole screen 100, then penetrates through the beam splitter 2 and is transmitted to the area array detector 8 through the fourier transform lens 7, a measurement light spot is formed on the area array detector 8, and the unified setting range can be determined through the measurement light spot. In implementation, the unified setting range, the screen hole diameter of the single-hole screen 100, and the like may be selected according to the detection parameter index to be achieved by the apparatus, and are not particularly limited.
The effect of the method is the same as the effect described above, and is not described herein again. In implementation, if the device is used as a set of integral use equipment, which is convenient for automatic use, the double-wedge mechanism 4 can be set to be cylindrical, two rotatable single wedge wedges 41 are provided in the cylindrical shape, and the device can further comprise an automatic controller, wherein the automatic controller is electrically connected with the area array detector 7, the linear translation stage 11 and a driving unit for driving the single wedge wedges 41 to rotate, and the device is calibrated to determine the range of the falling point of the measurement light spot on the area array detector 7; through a pre-written program and a unified setting range of the measuring light spots on the area array detector 7, the automatic controller controls the distance between different detection points on the surface of the optical device 5 to be measured, the automatic controller judges whether the measuring light spots corresponding to one detection point are formed in the unified setting range on the area array detector, if the measuring light spots are not formed in the unified setting range, the automatic controller can correct and drive the single wedge-shaped wedge 41 to rotate by combining with the actual falling point condition, so that the measuring light spots fall in the unified setting range. And outputting the rotation angle data to be used as a data basis for feeding back the surface shape of the optical device 5 to be measured. And (4) according to different standards, obtaining the required judgment data through data basis conversion to judge the surface shape of the optical device 5 to be measured.
An actual measurement example comprises the following steps: the vertex angle of the single wedge-shaped wedge 41 is set to be 5mrad, and when the double wedge mechanisms 4 are respectively reversely changed to +/-pi/6 when a first detection point is detected, the detection angle theta is-4.33 mrad; when the second detection point is detected, if the angle difference theta between the second detection point and the first detection point is 5urad, the angle difference between the reflected light beam and the incident light beam is 10urad, the two single wedge wedges 41 need to rotate to change the emergent light by about 5urad, the rotation angle can be calculated according to 2 x 0.000005/(sin (0.005) sin (pi/6)), and the rotation angles respectively rotate by about 4 mrad; that is, when the second detection point is detected, if the two single wedge wedges 41 are adjusted to rotate by about 4mrad respectively, so that the reflected light path returns, the angle θ between the second detection point and the first detection point is different by 5 urad.
In implementation, the top angle setting of the single wedge-shaped wedge 41 can be adjusted according to the measurement requirement, for example, when the range of 10mrad needs to be measured, the wedge with the top angle of 10mrad needs to be used, and is not particularly limited.
The aforementioned correction of the rotation angle of the double wedge mechanism 4 by measuring the actual formation position of the light spot to facilitate the rotational adjustment can be achieved by:
referring to fig. 5 again, since the angle measurement range is small (e.g., within ± 5mrad), the angle satisfies:
if the vertex angle of the wedge is gamma, and the angle of the emergent light path is adjusted to be (α, theta) through the wedge, the following can be calculated:
the double wedge is rotated by an angle of about δ 1, δ 2:
in actual detection, if the angle of the outgoing light path is adjusted by the double wedges to be (α, theta), the normal line of the detection point is inconsistent with the outgoing light path, and the angle of the light beam measured in the f-theta angle detection system is (2 delta α, 2 delta theta), the angle difference between the normal line of the detection point and the direction of the outgoing light path is obtained to be (-delta α, -delta theta), the normal direction angle of the detection point is (- α -delta α, -theta-delta theta), so that the direction of the outgoing light path can be (α + delta α, theta + delta theta) by rotating the wedges according to the method, so that an angle adjustment reference can be provided for auxiliary wedge rotation adjustment, more accurate derivation calculation according to geometric optics theory can be adopted (practical application significance is not great), when the wedge is used, the corresponding measurement angle value can be correspondingly changed due to the change of the corresponding detection position point after the wedge rotation adjustment, and the wedge rotation angle can be corrected for many times according to the data of the f-theta angle detection system to obtain more accurate detection results.
Finally, the above embodiments are only for illustrating the technical solutions of the present invention and not for limiting, although the present invention has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that modifications or equivalent substitutions may be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all of them should be covered in the claims of the present invention.
Claims (10)
1. Long-range optical surface shape of face detection device, including detection light path and be used for forming the f-theta angle detecting system who measures the facula, its characterized in that: in the detection light path, an incident light path directly incident to the surface of the optical device to be detected is provided with a double-wedge mechanism, the double-wedge mechanism comprises two single wedge wedges arranged at intervals along the incident light path, the incident light path penetrates through the two single wedge wedges, and the two single wedge wedges can independently rotate so as to change the angle of an emergent light path of the single wedge mechanism through rotation and enable the emergent light path to be incident to the surface of the optical device to be detected in a normal incidence mode.
2. The long-range optical surface profile inspection device of claim 1, wherein: the f-theta angle detection system comprises a Fourier transform lens and a planar array detector, the light source, the beam splitter, the Fourier transform lens and the planar array detector are fixedly arranged, the two planar mirrors and the double-cusp mechanism are arranged on the movable optical head, an emergent light beam provided by the light source is reflected to the two planar mirrors through the beam splitter, penetrates through the double-cusp mechanism after being reflected by the two planar mirrors to be incident on the surface of the optical device to be detected, is reflected by the surface of the optical device to be detected and returns to the beam splitter along an incident light path, and the reflected light beam penetrates through the beam splitter and is transmitted to the planar array detector through the Fourier transform lens to form the measuring light spot on the planar array detector.
3. The long-range optical surface profile inspection device of claim 2, wherein: the movable optical head comprises a shell, and the two plane reflectors and the double-wedge mechanism are arranged in the shell.
4. The long-range optical surface profile inspection device of claim 3, wherein: the movable optical head is installed on the linear translation table, the linear translation table is slidably arranged above the optical platform so as to drive the movable optical head to slide and detect an optical device to be detected, the optical device to be detected is arranged on the optical platform, and the light source, the beam splitter, the Fourier transform lens and the area array detector are fixedly arranged on the side wall of the optical platform.
5. The long-range optical surface profile inspection device of claim 2, wherein: the light source is a parallel light source to provide an emergent beam of parallel light.
6. The long-range optical surface profile inspection device of claim 5, wherein: the light source is an incoherent light source.
7. The long-range optical surface profile inspection device as set forth in any one of claims 1-6, wherein: the two single wedge wedges are adjacent, one surface, opposite to the two single wedge wedges, of each single wedge is a horizontal glass surface which is parallel to each other, and the other surface, opposite to the surface, of each single wedge is a wedge-shaped inclined glass surface, so that the distance between the two single wedge wedges which are arranged adjacently can be smaller.
8. The long-range optical surface shape detection method is characterized by comprising the following steps: the method is carried out on the basis of the long-range optical surface shape detection device as set forth in any one of claims 4-6, and comprises the following steps:
1) placing an optical device to be tested on an optical platform;
2) the linear translation stage drives the movable optical head to slide to a first detection point, an emergent light beam provided by the light source is reflected by the surface of the optical device to be detected, and a measurement light spot is formed on the area array detector;
3) rotating the two single wedge wedges to enable the emergent light path to be incident to the surface of the optical device to be measured in a normal incidence mode, and judging whether the measuring light spots are formed in a unified set range on the area array detector;
if the measuring light spot is formed in the unified setting range, outputting the rotation data of the two single wedge wedges;
if the measuring light spot is not formed in the unified setting range, continuing to rotate and adjust until the measuring light spot is formed in the unified setting range, and then outputting the rotation data of the two single wedge wedges;
4) the linear translation stage drives the movable optical head to slide to the next detection point, an emergent light beam provided by the light source is reflected by the surface of the optical device to be detected, and a measurement light spot is formed on the area array detector;
5) repeating the steps 3) and 4) until the set rotation data of the two single wedge wedges corresponding to all the detection points are output;
6) and obtaining the surface shape of the optical device to be measured through the obtained rotation data.
9. The method for detecting the surface shape of the long-range optical surface according to claim 8, wherein: before the step 1), the calibration operation of the device is further included, and the calibration operation comprises the step of determining the unified setting range through a measuring light spot formed on the area array detector by a reflection light path returned by the incident light path.
10. The method for detecting the surface shape of the long-range optical surface according to claim 9, wherein: the calibration operation comprises the following steps:
a) a single-hole screen is closely arranged on the beam splitter;
b) placing a calibration piece on the optical platform;
c) an emergent light beam provided by the light source penetrates through a screen hole of the single-hole screen, is reflected to the two plane reflectors through the beam splitter, penetrates through the double-wedge mechanism after being reflected by the two plane reflectors, is incident on the surface of the calibration piece, and is reflected by the surface of the calibration piece to form a reflection light path;
and adjusting the posture of the calibration part to enable the reflected light path to return along the original path of the incident light path, penetrate through the screen hole of the single-hole screen, penetrate through the beam splitter and transmit to the area array detector through the Fourier transform lens, and form a measuring light spot on the area array detector.
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